Due to advances in science and technology, UAV design has been more sophisticated. With the optical, ultrasonic and microwave sensors mounted on a UAV, the UAV can be used in entertainment, exploration, disaster relief, delivery, and even crime and war.
Due to the increasing effective distance of wireless remote control, the flight distance and altitude of the UAV increase. Therefore, it is a new discussion topic whether the UAV can fly safely beyond the visual range. In FIG. 1, which is a schematic diagram of Taiwan patent No. TWM518111, the system is a UAV active obstacle avoidance system which includes a transmitter 10, a microprocessor control board 11, a distance sensor 12, a signal receiver 13 and a UAV 14. The main body of the UAV automatic obstacle avoidance system is the microprocessor control board 11, wherein the microprocessor control board 11 is connected to each of the distance sensors 12. By using the measure results of distance sensor 12 and according to the obstacle avoidance conditions defined in a program, values of the controls signal of the UAV 14 are modified when necessary, so as to achieve the purpose of avoiding obstacles.
The obstacle avoidance system uses ultrasonic, optical sensors with infrared rays, laser or the like or radar to detect the relative distance. However, the obstacle avoidance system does not describe many functions of the radar. If the obstacle is not big enough or the weather is not good enough, then the obstacle avoidance performance of the obstacle avoidance system may be weakened. Further, the obstacle avoidance system is not mentioned to equip with position and inertial sensors, and thus the obstacle avoidance system has no automatic navigation function.